Delivery device with an expandable positioner for positioning a prosthesis

ABSTRACT

A prosthesis delivery device comprises a cannula having an expandable positioning device disposed at the proximal end thereof. A prosthesis is retained on the cannula distal of the expandable device. Expansion of the expandable device retains and centers the delivery device and the prosthesis carried thereon in the vessel and allows repositioning of the prosthesis without contacting the proximal end of the prosthesis with the vessel walls prior to deployment.

RELATED APPLICATIONS

The present application claims the benefit of the filing date under 35U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No.62/089,072, filed Dec. 8, 2014, which is hereby incorporated byreference.

BACKGROUND

The present invention relates to delivery devices for prostheses, suchas stents, grafts and stent grafts (collectively prostheses) in thevascular system of a patient. In particular, the invention relates to aprosthesis delivery device having an expandable positioner that allowscentering and repositioning of a prosthesis in a vessel prior todeployment.

SUMMARY

A prosthesis delivery device is described. In one example, the deliverydevice comprises a delivery cannula having at least one lumen extendingthere through and a proximal end. A nose cone dilator is disposed at theproximal end of the delivery cannula and an opening is formed in a wallof the nose cone dilator. The opening is in flow communication with thecannula lumen. An expandable positioner is disposed about the openingformed in the wall nose cone dilator. The expandable positionercomprises a wall defining an interior space, wherein the interior spaceof the expandable positioner is in flow communication with the at leastone cannula lumen via the opening formed in the wall of the nose cone.The positioner comprises a radially expanded condition and a radiallycontracted condition, such that flowing a fluid proximally through theat least one cannula lumen, through the opening formed in the wall ofthe nose cone dilator, and into the interior space of the positionermoves the positioner from the contracted condition to the expandedcondition.

In another example, a prosthesis delivery device is described. Thedelivery device comprises a delivery cannula having a longitudinal axisand an expandable proximal region, wherein the expandable proximalregion comprising a plurality of expandable wings. A prosthesisretention section is located on the delivery cannula distal to theexpandable proximal region, and a retractable sheath disposed about theprosthesis. The expandable wings are expanded radially outwardly byurging together a proximal end and a distal end of the expandableproximal region along the longitudinal axis.

A method of delivering a prosthesis is also described. In one example,the method comprises introducing a delivery device into a vessel. Thedelivery device comprises a delivery cannula having at least one lumenextending there through and a proximal end, a nose cone dilator disposedat the proximal end of the delivery cannula, a radially expandablepositioner disposed about a portion of the nose cone, a prosthesiscarried on the delivery cannula distal to the radially expandablepositioner and a retractable sheath disposed about the prosthesis. Themethod further comprises the steps of flowing fluid through the at leastone lumen to expand the expandable positioner, positioning the deliverydevice in the vessel, retracting the sheath to expose at least aproximal end of the prosthesis, releasing the proximal end of aprosthesis from the delivery cannula and releasing the distal end of theprosthesis from the delivery cannula.

An alternative method of delivering a prosthesis is also described. Themethod comprises introducing a delivery device into a vessel. Thedelivery device comprises a delivery cannula having a first lumenextending there through and a proximal end, a nose cone dilator disposedat the proximal end of the delivery cannula, a radially expandablepositioner disposed distally of the nose cone, a prosthesis carried onthe delivery cannula distal to the radially expandable positioner and aretractable sheath disposed about the prosthesis. The method furthercomprises expanding the positioner to position the delivery device inthe vessel, retracting the sheath to expose at least a portion of theprosthesis, releasing a proximal end of a prosthesis from the deliverycannula and releasing the distal end of the prosthesis from the deliverycannula.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the proximal end of the prosthesis deliverydevice having a radially expandable positioner.

FIG. 2 is an enlarged view of the proximal end of the delivery device ofFIG. 1.

FIG. 3a is an enlarged view of a proximal apex of a proximal end stentthat may be coupled to the proximal end of the delivery device.

FIGS. 3b-c illustrate twisting of a portion of the proximal end stent ofFIG. 3 a.

FIG. 4a shows a side view of the delivery device of FIG. 1 having aradially expandable positioner and a prosthesis located just distal ofthe positioner.

FIG. 4b shows the device of FIG. 4a after release of the proximal endstent.

FIGS. 5-11 illustrate one example of a procedure for delivering aprosthesis with a delivery device having an expandable positioner toallow centering and repositioning of the prosthesis before deployment.

FIGS. 12-13 show an alternative example of a delivery device having anexpandable positioner.

FIG. 14 is a cross-sectional view of the cannula used in the deliverydevice of FIGS. 1-2 and 4-11.

FIG. 15 is a cross-sectional view of the cannula used in the deliverydevice of FIGS. 12-13.

FIG. 16 is front view of the proximal end of the delivery device ofFIGS. 12-13.

FIGS. 17a-d illustrate side views of the attachment of the distal end ofa prosthesis to the delivery device.

DETAILED DESCRIPTION

The embodiments described in this disclosure will be discussed generallyin relation to deployment of prostheses, such as stents, grafts andstent grafts into a patient's vasculature, but the disclosure is not solimited and may be applied to other body vessels, organs or lumens.

In the present application, the term “proximal” refers to a directionthat is generally closest to the heart during a medical procedure, whilethe term “distal” refers to a direction that is furthest from the heartduring a medical procedure.

The term “stent graft” refers to a device that has a tubular body ofbiocompatible graft material and at least one stent fastened to thetubular body to define a lumen through the stent graft. The stent graftmay be bifurcated and/or may include fenestrations, side arms, or thelike. Other arrangements of stent grafts also are within the scope ofthis disclosure.

In one example, a delivery device is described that facilitates thepositioning and centering of the device in a vessel prior to release anddeployment of a prosthesis. In particular, the delivery device isoperable to keep one or more anchoring structures located on a bareproximal stent from engaging with the vessel wall prior to deployment byretaining the proximal end of the delivery device in the center of thevessel. For example, the delivery device may include a balloonintegrated into the flexible tip of the delivery device that can beinflated to retain the delivery device in the center of the vessel. Inanother example, the delivery device may include a malecot structurethat can be expanded to retain the delivery device in the center of thevessel.

During the delivery process, the delivery device is first guided to atarget location within the vasculature with a prosthesis retained on theproximal end of the delivery device. Once in position, the expandablepositioner is expanded to retain the delivery device in the center ofthe vessel. The prosthesis remains attached to the proximal end of thedelivery device, with the proximal stent retained radially inwardly onthe delivery device. The expandable positioner, whether a balloon,malecot, or some other expandable structure, has a diameter that exceedsthe diameter of any anchoring structures located on the proximal stent(such as barbs) so that the anchors are kept away from the vessel wallto prevent them from engaging the vessel, thus allowing the prosthesisto be adjusted or repositioned as needed. When the desired position isobtained, the expandable positioner can be returned to its unexpandedstate and the prosthesis fully released at the target location.

The prosthesis can be retained on the delivery device through varioustypes of attachment and release mechanisms. The proximal end attachmentand release mechanism, as described in more detail below, may include ahelix system that is shown and described in U.S. patent application Ser.No. 13/796,395, filed Mar. 12, 2013, which is incorporated by referencein its entirety herein. In another example, the proximal end attachmentand release mechanism may include a trigger wire or other structure ordiameter reducing tie(s) that releasably retains the proximal portion ofthe prosthesis on the delivery device before release.

The attachment and release mechanism that retains the distal end of theprosthesis on the delivery device may include a wireless medical devicerelease mechanism that is shown and described in U.S. patent applicationSer. No. 13/838,013, filed Mar. 15, 2013, which is incorporated byreference in its entirety herein. Other embodiments of exemplary distalend attachment and release mechanisms can similarly be found in U.S.patent application Ser. No. 13/835,877, filed Mar. 15, 2013, which isincorporated by reference in its entirety herein. In another embodiment,the distal end attachment and release mechanism may include a triggerwire or other structure that releasably retains the distal portion ofthe prosthesis on the delivery device before release.

FIGS. 1 and 2 illustrate the proximal end of a delivery device 100having a cannula 160, a tapered nose cone 102 having a proximal tip 104,and an expandable device 120 disposed about the distal end 110 of thenose cone 102. The nose cone surface 106 presents a smooth taperedsurface to facilitate entry into and movement through a body vessel. Asshown in an enlarged view in FIG. 2, an exemplary stent proximal endattachment and release mechanism 140 (see FIG. 1) is disposed at or nearthe distal end 110 of the nose cone 102 and on the cannula 160. Anexpandable device 120 is disposed about the distal end 110 of the nosecone 102 and is attached to the nose cone 102 by seals on the proximalend 122 and distal end 124. In this non-limiting example, the proximalend 122 of the expandable device 120 and the distal end 124 of theexpandable device 120 are secured to the outer surface of the nose cone102 using a suitable mechanism, such as adhesives, bonding, heatsealing, and the like. This expandable device 120 is disposed overentrance port 126 which provides an entrance for the flow of fluid fromthe second lumen 1420 of FIG. 14 as described further below.

As shown in FIG. 2, the attachment and release mechanism 140 for theproximal stent comprises coiled member 130, having a proximal end 132, adistal end 134, and a plurality of turns 136 disposed there between. Ina non-limiting example, the proximal end 132 of the coiled member 130 issecured to the outer surface 170 of the cannula 160 using a suitableattachment mechanism, such as a solder, weld, mechanical attachment,friction fit, crimp or combination thereof. Accordingly, the proximalend 132 of the coiled member 130 cannot move relative to the cannulaouter surface 170 of cannula 160. The proximal end 132 of the coiledmember 130 comprises a first diameter d1, which may be approximately thesame diameter, or slightly greater than, an outer diameter of thecannula 160. The distal end 134 of the coiled member 130 may comprise asecond diameter d2, which is greater than the first diameter d1 of theproximal end 132 of the coiled member 130. There is a separation or gapd3 between the distal end 134 of the coiled member 130 and the cannulaouter surface 170 of the cannula 160, as seen in FIG. 2.

The plurality of turns 136 are divided into a proximal series of turns138 a, which have the first diameter d1, and a distal series of turns138 b, which have the second diameter d2. The proximal series of turns138 a may be disposed in close proximity or abutting one another, asdepicted in FIG. 2. By contrast, the distal series of turns 138 b may bespaced apart from one another a greater predetermined distance denotedby spacing d4.

Turning now to FIGS. 3a-c , one example of a portion of a bare proximaltop stent 300 of a prosthesis 400 (FIGS. 4a-b ) is shown. The proximaltop stent 300 may be releasably engaged with the coiled member 130 ofattachment and release mechanism 140 described above. This type ofattachment system of the proximal stent to the delivery system is morefully described in U.S. application Ser. No. 13/796,395, filed Mar. 12,2013, and in particular, with reference to FIGS. 6-8, which applicationis incorporated by reference in its entirety. The proximal end 305 ofbare proximal top stent 300 includes at least one proximal apex 315having a region comprising an aperture, opening or eyelet 330.

The eyelet 330 may be formed within a suture loop 335 that is disposedat the proximal end of a proximal extension segment 340. The proximalextension segment 340 extends in a proximal direction away from the endregion 345, which end region 345 comprises an anchoring mechanism orstructure for attaching or engaging the stent with a vessel wall, suchas a barb 355 as shown in FIGS. 3a -c.

In one example, the suture loop 335 and the proximal extension segment340 comprise a wall thickness that is less than a wall thickness of theend region 345 having the barb 355, as best seen in FIG. 3a .Advantageously, the reduced wall thickness of the suture loop 335 andthe proximal extension segment 340 allows at least the suture loop 335to twist circumferentially to facilitate loading of the proximal end 305of the bare stent around the coiled member 130. In the non-limitingexample shown, the suture loop 335 twists in a circumferential directionabout 90 degrees between a first state shown in FIG. 3b and a secondstate shown in FIG. 3c . The suture loop 335 may twist greater than orless than 90 degrees as necessary or desired. Moreover, at least aportion of the proximal extension segment 340 may twist in thecircumferential direction as the suture loop 335 is circumferentiallytwisted.

The proximal extension segment 340 provides longitudinal separation ofthe suture loop 335 housing the eyelet 330 from the end region 345having the barb 355. Accordingly, when the eyelet 330 is threaded aroundthe coiled member 130, the proximal extension segment 340 provides alongitudinal spacing that reduces the likelihood of entanglement betweenthe coiled member 130 and the barb 355 formed in end region 345.

The proximal apex 315 shown in FIGS. 3a-3c may be provided on each andevery proximal end 305 the bare proximal top stent 300. Alternatively,the proximal apex 315 may be provided on fewer than all of the proximalends 305 of the bare proximal top stent 300, and the remaining proximalends 305 may be provided with only barbs or similar vessel engagingstructures such as the barb 355 pictured in FIGS. 3a -3 c, or theremaining proximal ends 305 may comprise other features or structures.

In FIGS. 4a and 4b , an exemplary coupling of a stent graft 400 to adelivery device 100 is shown. The stent graft 400 has an uncoupled statein which the stent graft 400 is positioned coaxially over the cannula160 with the proximal end 405 of the stent graft 400 longitudinallyspaced from the distal end 134 of the coiled member 130. Duringassembly, one or more suture loops 335 that are coupled to the proximalends or apices 430 of the bare proximal top stent 300 are threadedaround the distal end 134 of the coiled member 130. Such coupling may beachieved by rotating the cannula 160 in a clockwise direction until theproximal end 405 of the bare proximal top stent 300 is sufficientlycompressed in a radially inward direction, as depicted in FIG. 4a . Asthe gap d3 of FIG. 2 between the distal end 134 of the coiled member 130and the cannula outer surface 170 permits positioning of the coiledmember 130 through the suture loops 335 in a series of turns at thedistal end 134 of the cannula 160. This type of attachment system of theproximal stent to the delivery system is more fully described in U.S.application Ser. No. 13/796,395, filed Mar. 12, 2013 which isincorporated herein by reference.

One or more suture loops 335 are further accommodated within the spacingd4 (FIG. 2) between the distal series of turns 138 b. The suture loops335 are preferably coupled to the coiled member 130 in a manner in whichat least one suture loop 335 is positioned around at least one full turnof the distal series of turns 138 b and preferably around at least 1.5turns at the distal end 134 of coiled member 130, thereby reducing thelikelihood of inadvertent uncoupling of the at least one suture loop 335from the coiled member 130. The coupling shown in FIG. 4a secures thebare proximal top stent 300 to the cannula 160 via the coiled member 130in a manner that may subsequently facilitate insertion of a subassemblycomprising the cannula 160 and the stent graft 400 into a sheath 500. Asdescribed further below, the sheath 500 is configured to radiallyinwardly restrain the stent graft 400 for delivery to a target sitewithin a patient's anatomy.

The suture loops 335 may be coupled to every other proximal end or apex430 as shown in FIGS. 4a-b to restrain the bare proximal top stent 300and hold it in a radially inward or compressed configuration having areduced profile during delivery. In one example, the suture loops 335are not coupled to the second proximal ends or apices 440, which maycomprise barbs. By restraining the alternating proximal ends or apices430 using the suture loop(s) 335 coupled to the coiled member 130, thesecond proximal apices 440 may be indirectly pulled in a radially inwarddirection during delivery. In other words, the configuration of the bareproximal top stent 300 facilitates the indirect compression of theadjacent second proximal apices 440. Since only selected ones of theproximal ends or apices are restrained during delivery, the number ofsuture loop(s) 335 may be reduced.

The above description of the proximal end attachment and releasemechanism 140 which comprises at least one coiled member 130 toreleasably engage the proximal bare stent is not intended to belimiting, and one of skill would recognize that the delivery device maybe provided with one or more alternative mechanisms to releasably engagethe proximal top stent 300 and/or the stent graft 400 during deliveryand deployment, including but not limited to one or more trigger wires,diameter reducing ties and other attachment mechanisms that would berecognized by one of skill in the art.

FIGS. 5-11 illustrate one example of the delivery device 100 in use, andmore specifically, the positioning and centering of the delivery device100 and subsequent release of the stent graft 400 within a vessel. Asshown in FIG. 5, the stent graft 400 is loaded on the delivery device100 and compressed by sheath 500. In operation, the user guides thedelivery device 100 to a target location within the patient's body. Oncethe delivery device 100 is in a desired position, the operator expandsthe expandable device 120 to retain and stabilize the delivery device100 in the center of the vessel lumen 530 as shown in FIG. 6.

In one non-limiting example, the expandable device 120 may include aninflatable structure or balloon. The cannula 160 may include a firstlumen 1410 and at least a second lumen 1420 that run parallel to eachother through the center of the cannula 160 as shown in FIG. 14, whereinthe second lumen 1420 provides for the flow of fluid and/or gas to allowinflation or deflation of the expandable device 120. To inflate theexpandable device 120, fluid flows in a proximal direction through thesecond lumen 1420, through the entrance port 126 on the nose cone 102and into the expandable device 120. Fluid is contained in the expandabledevice 120 by attachments to nose cone 102 at the proximal end 122 anddistal end 124 and allows the expandable device 120 to inflate. Todeflate the expandable device 120, fluid exits out the expandable device120 through the entrance port 126 on the nose cone 102 and into thesecond lumen 1420 where it travels in a distal direction away from theexpandable device 120.

In further operation, the operator then withdraws the sheath 500 in thedistal direction as indicated by the arrow shown in FIG. 7 so that thebare proximal top stent 300 is at least partially exposed. In thisposition, the barbs 355 are kept away from the vessel lumen 530,allowing the user to reposition and adjust the longitudinal position ofthe stent graft 400 as needed prior to final deployment and/or release.When the desired position is obtained, the cannula 160 may be rotated(such as in a clock-wise direction as shown by the arrow in FIG. 8)until the at least one suture loop 335 is uncoupled from the coiledmember 130 (i.e. in a reverse manner from which the at least one sutureloop 335 was coupled to the coiled member 130). The bare proximal topstent 300 then may be deployed as shown in FIGS. 4a-b and 8. In analternative embodiment, the proximal end 405 of the stent graft 400 maybe radially restrained through the use of trigger wires that can becontained in at least one of the first and second lumens, andpreferably, in the first lumen 1410 of the cannula 160 of FIG. 14.

FIGS. 9-11 demonstrate the continued operation of the delivery device100 to release the distal end 410 of the stent graft 400. The distal end410 of the stent graft 400 is attached to the delivery device 100 by wayof at least one distal attachment and release mechanism 540 onpositioner 510 which engages a corresponding element at the distal end410, such as a looped portion 1710. However, as previously mentioned,the distal end of the stent graft may be releasably coupled to thedelivery device by other acceptable mechanisms including one or moretrigger wires, diameter reducing ties or combinations thereof As shownin FIG. 9, the expandable device 120 is deflated as the fluid containedin the expandable device 120 exits through the entrance port 126 throughthe second lumen 1420 in a distal direction. The sheath 500 is thenfully withdrawn and removed from the stent graft in a distal directionas shown by the arrow in FIG. 10. The full withdrawal of the sheath 500exposes the distal end 410 of the stent graft 400 as shown in FIG. 11.The distal end 410 of the stent graft 400 is then fully released byreleasing the looped portion 1710 from the distal attachment and releasemechanism 540 as also shown in FIG. 11.

FIGS. 17a-d are enlarged side views of the distal end of a prosthesiswith an exemplary distal attachment and release mechanism. As shownthere, the sheath 500 is transparent to allow objects covered by thesheath 500 to be visible. The sheath 500 may actually be opaque ortransparent or a combination thereof. Positioner 510 has a releasabledistal attachment and release mechanism 540 at the proximal end 520. Inthis example, the attachment and release mechanism comprises a capturewire 1720 on the positioner 510 which is bent to engage a looped portion1710 or other corresponding structure or configuration at the distal end410 of the stent graft 400.

While the sheath 500 is disposed over the capture wire 1720, the capturewire 1720 is prevented from straightening. A close fit of the sheath 500over the positioner 510 and capture wire 1720, as shown in 17 b,prevents the looped portion 1710 from releasing or becoming detachedfrom the capture wire 1720 while the sheath 500 is positioned over it.At least a portion of the capture wire 1720 is affixed to the positioner510. An unattached section 1750 of the capture wire 1720 may be free andnot attached to the positioner 510. For example, the capture wire 1720may include one or more bends in the unattached section 1750 when thesheath 500 covers the capture wire 1720. In the case of a single bend,the bend may be approximately 180 degrees. The unattached section of thecapture wire 1720 is held in the bent position by the presence of thesheath 500 where the unattached section 1750 is prevented fromstraightening out and removing the bend 1740.

The unattached section 1750 of the capture wire 1720 may include anatraumatic portion 1730 which may prevent damage to a vessel wall orbody cavity if the unattached section 1750 of the capture wire 1720contacts the vessel wall or body cavity. The atraumatic portion 1730 maytake any shape that prevents or minimizes damage to a vessel wall orbody cavity including, for example, a rounded ball, curved segment,curved end, or cushioned area.

The capture wire 1720 may be composed of any material capable ofdeforming and later returning to its un-deformed shape, such as bendingand later straightening, without any external force applied. The capturewire 1720 may consist of, for example, nitinol or polypropylenefilament. The length, thickness, and flexibility of the capture wire1720 may be varied depending on the application. For example, a thickeror less flexible capture wire 1720 may be used if the looped portion1710 applies a relatively large force to the capture wire 1720. A longercapture wire 1720 may be used if the diameter of looped portion 1710 isrelatively large or if the space between the proximal end 520 of thesheath 500 is relatively large.

FIG. 17d shows the sheath 500 withdrawn from the capture wire 1720. Thecapture wire 1720 may return to its un-deformed or unbent shapeautomatically upon removal of the sheath 500. For example, removal fromthe sheath from over the capture wire 1720 permits the capture wire 1720to be relieved from its bent shape and release loop 1710, consequentlyreleasing the distal end 410 of the prosthesis. After the distal end 410is released, the device 100 may be removed from the prosthesis and thebody vessel.

FIGS. 12, 13, and 15-16 illustrate another example of an expandabledelivery device 1200. Like numbers denote similar features to thatpreviously described. FIG. 12 provides an illustration of the expandabledelivery device 1200 before expansion, comprising cannula 160, a nosecone 102 having a proximal tip 104 and the proximal end attachment andrelease mechanism 140 with attached stent graft 400. Nose cone 102 has areverse distal taper 108 at its distal end 110. The nose cone surface106 presents a smooth tapered surface to facilitate entry into andmovement through a body vessel. An expandable device 1210 is located atthe proximal end of the cannula 160. The expandable device 1210 isdistal to the nose cone 102 but proximal to the proximal end attachmentand release mechanism 140. In one example, the expandable device 1210comprises a malecot or similar structure that may include expandablewings, ribs, walls, baffles or a combination thereof. As shownspecifically in FIGS. 12 and 13, the malecot has an expandable region1220 defined between the proximal end or circumference 1260 and thedistal end or circumference 1250. The expandable device 1210 includesgenerally parallel slits 1230 that define lateral margins of malecotwings 1240. FIG. 13 illustrates the deployment of the expandable region1220. The expandable region 1220 is deployed by urging the proximalcircumference 1260 and distal circumference 1250 of the expandableregion 1220 towards each other which causes the central region of themalecot wings 1240 to expand radially outwardly.

FIG. 15 illustrates one embodiment of a cross-sectional view of thecannula 160 used in the expandable delivery device 1200. An innercannula 1510 is disposed within cannula 160 and is attached to thedistal end 110 of the nose cone 102. In this embodiment, the expandableregion 1220 is deployed by withdrawing the inner cannula 1510 in adistal direction relative to the cannula 160 which brings the proximaland distal ends 1260, 1250 closer together. In another embodiment, theexpandable delivery device 1200 does not have an inner cannula 1510 andthe expandable region 1220 is instead deployed by withdrawing a triggerwire (not shown) that is attached to the proximal end of the cannula160. FIG. 16 shows a front view of the proximal end of expandabledelivery device 1200 when the expandable malecot region 1220 isdeployed.

Like the expandable device or balloon 120 described above, theexpandable region 1220 retains and stabilizes the delivery device 100 inthe center of the vessel lumen 530. This facilitates the positioning ofthe stent graft 400 as necessary. Once the stent graft 400 is deployed,the expandable delivery device 1200 can be withdrawn through the stentgraft 400 by first moving the inner cannula 1510 in a proximal directionto pull the malecot wings 1240 radially inwardly such that the malecotdevice 1210 is flattened in a more slender profile for easy removal fromthe vessel.

An expandable positioning structure 120, 1200, which facilitatescentering of the delivery device 100, achieves several advantages,including, without limitation, providing the user with more control inachieving accurate deployment of the prosthesis within a tortuousdeployment zone. In one non-limiting example, providing the deliverydevice 100 with an expandable structure facilitates the centering of theproximal end of the delivery device and the proximal bare stent of thestent graft prior to deployment in a vessel lumen. In doing so, anyanchoring structures such as barbs are prevented from prematurelyengaging with a vessel wall, thus allowing the user to reposition thestent graft prior to its final release from the delivery device.Further, the expandable structure can also serve to expand the sealstents located, for example, in the body of the prosthesis, which wouldeliminate the need to re-insert another inflatable structure, such as aballoon, after implantation to fully expand the implanted prosthesis.

While particular elements, embodiments, and applications of the presentinvention have been shown and described, it is understood that theinvention is not limited thereto because modifications may be made bythose skilled in the art. It is therefore contemplated by the appendedclaims to cover such modifications and incorporate those features whichcome within the spirit and scope of the invention.

1. A prosthesis delivery device comprising: a delivery cannula having atleast one lumen extending there through and a proximal end; a nose conedilator disposed at the proximal end of the delivery cannula, and anopening formed in a wall of the nose cone dilator, wherein the openingis in flow communication with the at least one cannula lumen; anexpandable positioner disposed about the opening formed in the wall ofthe nose cone dilator, the expandable positioner comprising a walldefining an interior space, wherein the interior space of the expandablepositioner is in flow communication with the at least one cannula lumenvia the opening formed in the wall of the nose cone, wherein thepositioner comprises a radially expanded condition and a radiallycontracted condition; and wherein flowing a fluid proximally through theat least one cannula lumen, through the opening formed in the wall ofthe nose cone dilator, and into the interior space of the positionermoves the positioner from the contracted condition to the expandedcondition.
 2. The delivery device of claim 1 wherein the expandablepositioner comprises an inflatable device.
 3. The delivery device ofclaim 1 wherein the expandable positioner comprises a balloon.
 4. Thedelivery device of claim 2 wherein the at least one lumen is in flowcommunication with the inflatable device.
 5. The delivery device ofclaim 1 wherein the expandable positioner comprises a proximal end and adistal end, and wherein the proximal and distal ends of the positionerare secured to an outer surface of the nose cone dilator.
 6. Thedelivery device of claim 1 further comprising a prosthesis carried onthe delivery cannula.
 7. The delivery device of claim 6 wherein theprosthesis comprises a stent graft comprising a proximal bare stent. 8.The delivery device of claim 7 wherein the proximal bare stent comprisesat least one anchoring mechanism configured to engage a vessel wall. 9.The delivery device of claim 8 wherein the at least one anchoringmechanism of the bare stent is prevented from engaging a vessel wallwhen the positioner is in an expanded configuration.
 10. A prosthesisdelivery device comprising: a delivery cannula having a longitudinalaxis and an expandable proximal region, the expandable proximal regioncomprising a proximal end and a distal end and a plurality of expandablewings extending between the proximal and distal ends; wherein theexpandable wings comprise a radially outwardly expanded condition and aradially inwardly contracted condition, and wherein the expandable wingsare expanded radially outwardly by urging together the proximal anddistal ends of the expandable proximal region along the longitudinalaxis.
 11. The delivery device of claim 10 wherein the expandableproximal region comprises a malecot.
 12. The delivery device of claim 10further comprising a prosthesis retained on the delivery cannula,wherein the prosthesis has a proximal end releasably attached to thecannula.
 13. The delivery device of claim 12 wherein the prosthesiscomprises a stent graft comprising a proximal bare stent.
 14. Thedelivery device of claim 13 wherein the proximal bare stent comprises atleast one anchoring mechanism configured to engage a vessel wall. 15.The delivery device of claim 14 wherein the at least one anchoringmechanism of the bare stent is prevented from engaging a vessel wallwhen the expandable proximal region is in an expanded configuration. 16.A method of delivering a prosthesis comprising: introducing a deliverydevice into a vessel, the delivery device comprising a delivery cannulahaving at least one lumen extending there through and a proximal end, anose cone dilator disposed at the proximal end of the delivery cannula,a radially expandable positioner disposed about a portion of the nosecone, a prosthesis carried on the delivery cannula distal to theradially expandable positioner, a retractable sheath disposed about theprosthesis; flowing fluid through the at least one lumen to expand theexpandable positioner; positioning the delivery device in the vessel;retracting the sheath to expose at least a proximal end of theprosthesis; releasing the proximal end of a prosthesis from the deliverycannula; and releasing the distal end of the prosthesis from thedelivery cannula.
 17. The method of claim 16 further comprisingwithdrawing the delivery device from the vessel.
 18. A method ofdelivering a prosthesis comprising introducing a delivery device into avessel, the delivery device comprising a delivery cannula having a firstlumen extending there through and a proximal end, a nose cone dilatordisposed at the proximal end of the delivery cannula, a radiallyexpandable positioner disposed distally of the nose cone, a prosthesiscarried on the delivery cannula distal to the radially expandablepositioner, a retractable sheath disposed about the prosthesis;expanding the positioner to position the delivery device in the vessel;retracting the sheath to expose at least a portion of the prosthesis;releasing a proximal end of a prosthesis from the delivery cannula;releasing the distal end of the prosthesis from the delivery cannula.19. The method of claim 18 wherein the radially expandable positionercomprises a malecot having a proximal end and a distal end.
 20. Themethod of claim 18 wherein the delivery cannula further comprises asecond cannula coaxial with and longitudinally moveable relative to thedelivery cannula.
 21. The method of claim 20 wherein the proximal end ofthe expandable positioner is attached to the second cannula and thedistal end of the expandable positioner is attached to the deliverycannula and wherein the method further comprises moving the secondcannula distally to urge the proximal and distal ends of the positionertowards each other thereby expanding the expandable positioner.